1. Field of the Invention
This invention generally relates to a steam generator with a water lance sprayer, or blower, for cleaning heat exchange surfaces, and more particularly for cleaning a combustion-chamber heat-transfer surface in a steam boiler. Such a water lance blower can have an outlet opening swivellably supported in a wall of the steam generator, with the rear parts thereof swivellably suspended for movement at the mounting wall.
2. Background Information
The cleaning of the combustion chambers of steam boilers having a high capacity, during operation, can be achieved, among other methods, with the aid of water lance blowers which can be mounted on a first wall of the steam boiler to throw a concise water jet, through the combustion chamber, and against the opposite wall. The contaminations of soot, slag and ash can then be peeled off due to the kinetic energy of the water jet hitting the surfaces, and also as a result of the thermal shock caused when the cooler water hits the heated surfaces of the exchanger.
To enable such a cleaning, the blowpipe, provided with a concentric spray nozzle, has been linked via a roller guide, with a drive for carrying out superimposed movements of the blow pipe, in an articulated way. For cleaning purposes, the water lance blower can be guided through a wall of the combustion chamber at an opened hatch, or the blowpipe can be entered into the combustion chamber through a piece of pipe supported in the hatch. Then, subsequent to the cyclic cleaning process, the water lance blower will typically be swung out or moved backward linearly, to remove the pipe from the combustion chamber, and thereby protect the blowing nozzle thermally and mechanically. Such a procedure, however, requires expensive equipment which is susceptible to trouble and, apart from that, renders it very difficult to automate the cleaning process. Moreover, with such solutions, multiple deflections, or bends, are needed in the water supply system, which deflections can cause high losses of water pressure ejected from the nozzles.
For avoiding the leakage of air into the steam boiler, and also for preventing contamination from exiting out of the steam boiler, the pipe passage through the combustion-chamber wall must preferably be as tight as possible.
For sealing longitudinally shiftable and rotatable jet pipes, it is known that the jet pipe can be passed through a stuffing box which is screwed to the face plate of the soot blower, as is described by Federal Republic of Germany Patent No. 17 51 511. This type of solution is essentially applicable, however, only to rigid water lance blowers.
For swivel-type water lance blowers, it is known that the blower head can be supported in a hatch of the combustion-chamber wall by means of a ball joint as is disclosed by German Democratic Republic Patent No. 145 476. With this solution, it is however disadvantageous that the hatch in the combustion-chamber wall must be divided horizontally and inserted into a machined spheroidal bore of a ball joint. Due to the entry of impurities into the sliding surfaces of the ball joint, the sliding surfaces tend to wear very quickly, so that the service life will typically be very short and the sealing and swivel function cannot be ensured any longer due to the fact that the ball joint gets jammed.
For exchanging the ball joint, the entire hatch must be removed. Thus, the removal of the hatch would provide an opening in the chamber surfaces, and the steam boiler essentially has to be put out of service for this purpose, so that contaminants do not leak out of the combustion chamber.
With another known water lance blower, the blowpipe is not required to be moved axially any longer, the diameter of the pipe passage through the hatch is reduced, and a self-cleaning effect is achieved between the sliding parts of the pipe passage. Such an arrangement is shown by German Democratic Republic Patent No. 235 102.
This is constructively achieved by a blow-through cylinder which is rigidly flange-mounted to the front of the blowing nozzle, and the outlet opening of the blowing nozzle is introduced into the blow-through cylinder. The blow-through cylinder is rigidly fastened in the ball joint, formed by a ball segment, and, in its free part, is slotted or provided with bores.
With this type of water lance blower, it is disadvantageous that the self-cleaning effect of the ball joint have not been found to be sufficient. The partition of the joint proves to be disadvantageous with regard to the heat admission due to the different expansions of both the halves. In spite of the design of a swivel-type roller guide, even with this solution, in the combustion chamber, no exact rectangular blowing pattern can be achieved on the opposite combustion-chamber wall by the ejected stream.